With the rapid development of information technology and the electronic industry, a plethora of handheld electronic devices (e.g., laptop computers, cell phones, personal digital assistants (PDAs), portable audio players, voice navigation devices, handheld game consoles, etc.) are now available at more and more affordable prices and with ever smaller dimensions. These handheld electronic devices can be easily carried around to provide their users with all kinds of handy functions and bring about tremendous convenience in daily life.
As handheld electronic devices nowadays are increasingly thinner, the space therein for installing loudspeakers decreases. In response, related manufacturers have spared no effort in reducing the spatial volume of loudspeakers, with a view to providing a compact loudspeaker that can fit in the tiny space inside a handheld electronic device. Take a cell phone with a small built-in loudspeaker for example. Referring to FIG. 1, a cell phone 1 includes a housing 11 and a loudspeaker 12. The housing 11 is provided therein with a receiving space 110 and has a lateral surface formed with a loudspeaker fixing hole 111. The loudspeaker 12 includes a frame 121 whose outer rim (i.e., the rim adjacent to a conical diaphragm 122) is fixed to the loudspeaker fixing hole 111, thereby securing the loudspeaker 12 to the housing 11. As a result, the frame 121 and a damping membrane 123 therein, as well as a coil 124 and a magnetic element 125, are received in the receiving space 110. The housing 11 has another lateral surface installed with a display screen 13 and a plurality of pushbuttons 14. The loudspeaker 12, the display screen 13, and the pushbuttons 14 are respectively and electrically connected to a circuit board 15 fixedly provided in the receiving space 110. When a user presses the pushbuttons 14 and thereby instructs the circuit board 15 to drive the loudspeaker 12 for sound reproduction, the circuit board 15 transmits an audio signal current to the coil 124 of the loudspeaker 12. Consequently, the coil 124 is magnetized to produce an electromagnetic effect, and an attractive or repulsive force is created by magnetic lines generated from the coil 124 and magnetic lines generated from the magnetic element 125 fixed to the periphery of the coil 124. As the audio signal current input to the coil 124 varies in magnitude and direction, the conical diaphragm 122 is driven to vibrate reciprocally, causing the loudspeaker 12 to make sound that propagates outward from the housing 11.
The frame 121, the conical diaphragm 122, the damping membrane 123, the coil 124, and the magnetic element 125 are indispensable components when making the loudspeaker 12 with existing techniques. However, such components, particularly the frame 121, the conical diaphragm 122, and the damping membrane 123, take up a huge amount of space and make it impossible to downsize the loudspeaker 12 effectively. On the other hand, the frame 121 is made of metal and therefore weighs considerably. Once the loudspeaker 12 equipped with the frame 121 is installed in the cell phone 1, the overall weight of the cell phone 1 is increased, which may reduce consumers' willingness to purchase the cell phone 1 and carry it with them. In consequence, the competitiveness of the assemblers and manufacturers of the cell phone 1 is impaired, which is undesirable not only to the assemblers and manufacturers, but also to users in general.
Moreover, as the loudspeaker 12 in the cell phone 1 must have small dimensions, the sound generated by the loudspeaker 12 has a low acoustic volume and high directivity. In other words, the highest volume and the sound of angle of the loudspeaker 12 are limited. As a result, the user may have problem hearing a loud and clear sound from the cell phone 1. Even worse, the user may have to be right in front of the handheld electronic device to hear only a vague sound, and nothing can be heard if the user is beside the handheld electronic device.
Therefore, the problem to be addressed by the present invention is to break through the bottleneck of existing loudspeaker manufacturing technology and design a novel loudspeaker capable of substantially reducing the spatial volume and overall weight of a device equipped with the loudspeaker; producing the optimal sound effects in terms of tone quality, acoustic volume, and directivity; and allowing users in front of and beside the device to hear clearly the sound generated thereby.